J. M. MACFARLANE ON VEGETABLE AND ANIMAL CELLS. 591 
research, viz., the formation of the nuclear spindle or barrel, and the transfor- 
mations of the nuclear substance during the process. No one could venture to 
doubt that these are often complex, in view of the beautiful investigations of 
STRASBURGER ; but the question is, Do these occur to an equal extent in all 
plants, and in all the tissues of them? Before answering this, let us ascertain 
for what end they exist. Setting aside SrTRASBURGER’s nuclear plate and disc 
phase as something which, though occasionally, is not always present, the 
study of various plants has convinced me that the spindle or barrel is merely 
a scaffolding thrown across the space between the halves of the dividing 
nucleus, the equator of this barrel, as its outward bulging progresses, coming 
ultimately to span the inner surface of the cell wall. It thus helps the 
protoplasm in its work of depositing the septum, and its presence is most 
definite and marked where vacuolation has most occurred. In cells filled with 
protoplasm, such as those of Chara, near the apex, no need exists for a: complex 
structure of this kind, and while StrasBurcer figures, and TREuB and ScHMIDT 
believe in, indirect division, I have, like Jonow, only seen such an appearance 
as would result from the separation of.a rather viscid body like the nucleus,, 
whose substance is traversed probably by delicate intranuclear threads. There 
seems undoubtedly to be a fibrous network ramifying through the nuclear. sub- 
stance of vegetable cells, judging from their appearance in the resting state, 
both when fresh and stained, as also in the dividing state, when these fibres are 
the most evident parts of the nuclear spindle. 
In division they must of necessity be apparent if present, and the less dense 
the medium by which they are surrounded the more strongly will they stand 
out to view. Thus we have the very sharply defined spindles in the vacuolated. 
cells of Lqguisetum limosum and Spirogyra nitida, but if the enveloping medium 
be nearly or quite as dense as the fibrils, the less evident will these appear, and 
as proof of this I would cite the cortical cells at the apex of the stem in 
Equisetum limosum, which are filled with protoplasm, and in which either 
fresh or stained spindles can be observed, but only by careful shading of the 
light. In young Chara cells this is even more striking, for it is only by skilful 
adjustment and shading of the light that between two nuclei pretty widely 
separated, but with no cell wall, or but a mere trace of it, between, delicate 
radiating strize could be detected. 
PROTOPLASM, CELL WALL.—In the formation of the cellulose septum N AEGELI’s 
conclusion, long ago expressed, that “ the cell membrane is an investment lying 
upon the surface of the contents, and secreted by them,” is being surely 
verified, though, as we have seen, it may be in a more complicated manner 
than he imagined, particularly in vacuolated ‘cells. 
Multinucleolar and Multinuclear State.—We will now deal with the very 
peculiar phenomenon, which I hope to show occurs more or less in all plants, 
